1. Field of the Invention
The present invention generally relates to image sensors, and more particularly, to complementary metal oxide semiconductor (CMOS) image sensors that use a method to permanently encode a watermark in a video data output stream.
2. Background Information
Watermarks, such as those found in video content, are used for a variety of purposes. They serve to identify copyrights to the video content and to identify in some manner the author of the original work, thereby lending credence and validity to the substance of the work. In video recordings and on broadcast television (TV), watermarks are typically located in the bottom right corner of the TV screen, and therefore serve to identify the broadcast network or serve a promotional purpose.
Video watermarks are added in a separate post-processing step to the raw video stream before the signal/stream is broadcast. Typically, an organization""s logo or other distinguishing mark is reduced to an outline having an appropriate size for the video image, and the outline is then combined arithmetically in the luminance channel with the incoming video stream. The resulting video image now has a watermark that allows the majority of the original video image to be seen through the watermark, but in a manner that allows the watermark to be clearly discernable. Similarly, the chrominance channel can be altered to render a watermark in color.
However, this separate post-processing step is cumbersome and requires extra equipment. Furthermore, because the watermarks are added to the video data stream or images during this post-processing step, the watermarks suffer from a lack of permanence. That is, subsequent processing or counterfeiting to edit/delete the watermark can be difficult to detect, since both the legitimate process to apply the watermark and the subsequent illegitimate editing/deletion of the watermark are performed in a post-processing manner on the video data stream or images. Therefore, improvements are needed in adding watermarks to images and/or video data streams.